Frank Solutions for Chapter 7 Circulatory System Class 10 Biology ICSE

Exercise


1. What is circulatory system? Describe the circulatory system of humans.
Answer
Circulatory system: It is a system of organs that takes part in the flow of materials in the body of an organism inside an extracellular fluid.
Circulatory system in humans:
  1. The right atrium receives deoxygenated blood from all the parts of the body through large veins called vena cava.
  2. When the right atrium is full of blood, it contracts and the blood is forced into right ventricle.
  3. When the right ventricle is full of blood, it contracts and the blood is pumped into the pulmonary trunk.
  4. From right ventricle, the pulmonary artery carries the blood to the lungs for oxygenation.
  5. The oxygenated blood returns to the heart via pulmonary veins that empty into the left auricle.
  6. When the left auricle contracts, the blood passes into the left ventricle by the opening of bicuspid valve.
  7. On contraction of the left ventricle, the blood is pumped into the artery called aorta.
  8. The aorta branches into vessels which transports blood to the heart and all the body parts.

2. Explain the following:

(i) Why is the SA node called the pace-maker of the heart?
(ii) Why is there no mixing of deoxygenated and oxygenated blood in the human heart normally?
(iii) Why is the closed circulatory system more efficient than the open system?
(iv) Why does the left ventricle possess a thicker wall than the right ventricle?

Answer

(i) The SA is also called the pacemaker because it establishes the basic frequency at which the heart beats. It starts each heart beat and sets the pace for the whole heart.

(ii) There is no mixing of deoxygenated and oxygenated blood in the human heart because of double circulation of blood where the blood passes twice through the heart and the right half of the heart is concerned with pumping deoxygenated blood while the left is concerned with pumping of oxygenated blood.

(iii) The closed circulatory system is more efficient than the open system because in closed system the blood flows inside arteries or veins all the time which stops the mixing of blood with other bodily fluids and helps the transport of the blood around the body.

(iv) The left ventricle possess a thicker wall than the right ventricle because it pumps the blood at a higher pressure since blood from the left ventricle goes to all areas of the body while the right ventricle only has to pump blood to the lungs which is a much shorter distance, therefore less pressure is required.

3. What are the differences between artery and vein?
Answer
Difference between Artery and Vein
Artery Vein
1. It is a type of blood vessel having thick muscular walls. 1. It is a type of blood vessels having thin muscular walls.
2. It contains oxygenated blood. 2. It contains deoxygenated blood.
3. It carries blood away from the heart. 3. It brings the blood to the heart.

4. What are the functions of blood plasma?
Answer
The functions of blood plasma : It transports gases and other materials, maintains blood pH, body immunity, body heat regulation and also regulates the osmotic pressure of the blood.

5. What is the double circulation?
Answer
Double circulation means during one circulation blood passes twice through the heart. It includes both pulmonary and systemic circulation. It is necessary as it keeps oxygenated and deoxygenated blood separate.

6. What are the materials carried by the blood?
Answer
The materials which are carried by the blood are: oxygen, carbon dioxide, water, digested food, organic wastes, hormones and antibodies.

7. What is the main function of erythrocytes?
Answer
The main function of erythrocytes is to transport the respiratory gases - Co2 and O2.

8. Name the following:

(i) The soluble protein present in the blood plasma responsible for clotting.
Fibrinogen

(ii) The process by which leucocytes engulf and destroy bacteria.
Phagocytosis

(iii) The iron containing pigment in the erythrocytes.
Hemoglobin

(iv) The phase of the cardiac cycle in which auricle contracts.
Auricular systole

(v) The study of blood vascular and lymphatic system.
Angiology

(vi) The inflammation of pericardium.
Pericarditis

(vii) The valve of right auriculo-ventricular aperture.
Tricuspid valve

(viii) In embryological stage right and left auricles are communicated by.
Foramen ovale
(ix) Abnormal rise in RBC number.
Polycythemia

(x) The first heart sound.
Lubb

9. Select the odd one in the following:
(i) RBC, WBC, Blood platelets, Histone.
(ii) Tricuspid, Bicuspid, Semilunar, Foramen ovales.
(iii) Artery, Vein, Capillary, Nerve.
(iv) Monocytes, Lymphocytes, Basophils, RBC
(v) Prothrombin, Thrombin, Fibrinogen, Albumin.
Answer
1. Histone
2. Foramen ovales
3. Nerve
4. RBC
5. Albumin

10. Refer to fig. 7.3. and answer the following questions:
(i) Impure blood is received by
(ii) Which chamber has thickest wall
(iii) Function of bicuspid value
(iv) Function of tricuspid value
Answer
(i) Inferior vena cava, superior vena cava and coronary sinus
(ii) Ventricles
(iii) Function of bicuspid valve: It prevents the reverse flow of blood from the left ventricle into the left auricle.
(iv) Function of tricuspid valve: It prevents the reverse flow of blood from the right ventricle into the right auricle.

11. Label the following diagram:
Answer

12. Match the terms in column I with terms in column II
Column I Column II
(i) Left auricle (a) Clotting
(ii) Right auricle (b) Thebesian value
(iii) Left ventricle (c) Pulmonary vein
(iv) Right ventricle (d) Aorta
(v) Fibrin (e) Pulmonary arch
Answer
Column I Column II
(i) Left auricle (c) Pulmonary vein
(ii) Right auricle (b) Thebesian value
(iii) Left ventricle (d) Aorta
(iv) Right ventricle (e) Pulmonary arch
(v) Fibrin (a) Clotting

13. Choose the correct answer:
(i) How much blood is present in an average person?
(a) 1 l
(b) 2 l
(c) 4 l
(d) 5 l
Answer
(d) 5 l

(ii) Which chamber of the heart has the thickest wall?
(a) Right atrium
(b) Left atrium
(c) Left ventricle
(d) Right ventricle
Answer
(c) Left ventricle

(iii) Exchange of material between blood and interstitial fluid occurs only at the
(a) veins
(b) capillaries
(c) arteries
(d) venule
Answer
(b) capillaries

(iv) Both erythrocytes and leucocytes form in the
(a) bone marrow
(b) thymus
(c) tonsil
(d) lymph node
Answer
(a) bone marrow

(v) The life-span of RBC is
(a) one month
(b) 100 days
(c) 120 days
(d) 100 hours
Answer
(c) 120 days

(vi) The mammalian heart is
(a) myogenic
(b) neurogenic
(c) digenic
(d) none of these
Answer
(a) myogenic

(vii) In mammals the opening of postcaval in the right auricle is guarded by
(a) Eustachian valve
(b) auricles
(c) ventricle
(d) heart
Answer
(a) Eustachian valve

(viii) Bundle of 'His' is found in
(a) inus venosus
(b) auricles
(c) ventricle
(d) heart
Answer
(c) ventricle

(ix) The rate of heart beat per minute in a normal man is
(a) 60-70
(b) 70-80
(c) 80-90
(d) 90-100
Answer
(b) 70-80

(x) Which of the following engulfs pathogen rapidly?
(a) Acidophils
(b) Basophils
(c) Monocytes
(d) Neutrophils
Answer
(c) Monocytes

(xi) The amount of water present in blood plasma is
(a) 60%
(b) 70%
(c) 80%
(d) 90%
Answer
(d) 90%

(xii) English physician who discovered blood circulation was
(a) J.C. Bose
(b) A. Vesalius
(c) William Harvey
(d) H.G. Khurana
Answer
(c) William Harvey

(xiii) Which of the following is termed as the 'graveyard' of R.B.C.?
(a) Liver
(b) Spleen
(c) Kidney
(d) Bone marrow
Answer
(b) Spleen

(xiv) The E.C.G. is used to detect
(a) heart attack
(b) heart block
(c) coronary thrombosis
(d) all the above
Answer
(d) all the above

(xv) Universal blood donor group is
(a) A
(b) B
(c) AB
(d) O
Answer
(d) O

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